31 March 2023
Colony losses plateau at similar level to last year
New Zealand beekeepers once again reported that the Varroa destructor mite is the most common reason for overwintering hive losses, according to the recently released New Zealand Colony Loss Survey.
The overall colony loss rate during winter 2022 was 13.5 per cent: almost identical to the loss rate in winter 2021. While loss rates have levelled off, they have levelled off near the highest recorded rates since the survey began in 2015, and the rate of suspected varroa-related losses continues to increase.
The survey estimates that 6.4 per cent of all living colonies (nearly half of all colony losses) were lost to suspected varroa and related complications over the 2022 winter. This is a 20 per cent increase from the 2021 rate of 5.3 percent. In contrast, losses attributed to queen problems, wasps and suspected starvation in 2022 were close to their long-term averages.
Varroa management rates amongst respondents improved considerably. 4.4 per cent of beekeepers said they didn’t treat for varroa in the 2020-21 season, while the latest survey shows that number dropped to only 1.5 per cent of beekeepers that didn’t do any varroa management in the 2021-22 season. In contrast to 2021, every beekeeper with more than 50 colonies treated for varroa in 2022.
In the survey beekeepers who lost colonies to varroa were asked what they thought went wrong. The most common answer was ‘re-invasion’. More than 38 per cent of survey respondents said that they treated for varroa more than once during autumn.
Barry Foster of the Apiculture New Zealand Science Focus Group says this is a timely reminder to beekeepers to “monitor, monitor and monitor their hives for mites.”
See https://www.mpi.govt.nz/dmsdocument/56194-2022-Colony-Loss-Survey-infographic for the NZ Colony Loss Survey infographic